I have successfully connected to the Internet in wired LAN, but have been having difficulty activating the wireless LAN.
First, there is no command such as iwlist or iwconfig used in RazBian, and /etc/wpa_supplicant does not exist either.

I do not know what to do to activate the wireless LAN.
Please let me know if you know anyone.

You started two very similar threads at the same time, but it makes more sense to keep it all discussion in the same thread. The significant text from your other thread (now deleted) is:

I built a Linux Kernel on the OPTEE site (https://github.com/OP-TEE/build/blob/ma ... cs/rpi3.md) and then flashed it on my microSD.
In the case of wired LAN, it works well, but there are difficulties in setting up wireless LAN.
First, when I run ifconfig, eth0 appears, but wlan0 does not exist.
I do not see wlan0 when I do ifconfig after adding wlan related information to / etc / network / interfaces.
And wpa_supplicant also does not exist. Therefore, commands such as iwconfig and iwlist do not exist.
Of course, wifi works well if you run it with Razbian rather than OPTEE Linux Kernel.

I have no idea what the problem is. Please let me know if anyone knows how.

You might have more luck asking for advice from the OPTEE community - they will be much more aware of how things are supposed to work - but you could start by adding the utilities from the iw repo. wpa_supplicant doesn't seem to have a canonical git repo, but http://www.linuxfromscratch.org, a useful-looking site, has links to the source and some basic instructions here.